Production of aluminium chloride



Oct. 13, 1964 2 I L. ,1. DERHAM 3,152,864

I Q PRODUCTION OF ALUMINIUM CHLORIDE Filed Feb. 25, 1963 The first part of the reaction vessel 3,152,864 PRODUCTEON F ALUMINHUM CHLQREDE Leslie Jack,Derham, Avonmouth, England, assignor. to "The National Smelting Company Limited, London,

England V Filed Feb. 25, 1963, Ser. No. 260,616 Claims-priority, applicationfl glgaat Britain, Mar. 7, 1962,

2 2 Claims: (Cl. as -as This invention relates to the production of anhydrous aluminium chloride either in vapour form or solid form and to apparatus therefor.

, As the'metal circulates in part 1b ofthe-vessel chlorine gas is introduced through achlorineinlet pipe 3 below the surface ofthe alloy. The heatof'formation of aluminium chloride is sufiicient to maintain the necessary temperature during operation, so no further heating is required, in fact cooling coils 7, sixteen are provided so that the alloy circulating'rtopart 1a of thevessel (by' i virtue of the circulation induced by pump 5 pumping alloy through pipe 4 and gate 6) can be kept within the above temperature limits. To prevent condensation of aluminium chloride in part 1b of vessel thetemperature at the top of the vessel is maintained slightly above 2.00

C. The condensing vessel 10 is maintained at a tempera- The invention consists of a method of preparing anhydrous aluminium chloride in which chlorine gas is passed through a molten zinc-aluminium alloy. If the solid is desired, the aluminium chloride vapour thus producedis condensed. This reaction is preferably carried out between 430 C. and 500 C.

Preferably the aluminium chloride vapour is passed .through a layer of pieces of aluminium, e.g., before condensation, to exclude chlorine from the vapour or solid product. I

The invention further consists of apparatus for carrying out the method comprising a corrosion-resistant vessel or vessel" portion supplying zinc-aluminium alloy and a secondcorrosion-resistant vessel ortvessei portion con nected to receive a circulating flow of alloy from the first and having aconnection for feeding chlorine into the alloy contained therein. If the solid producti s required a further corrosion-resistant vessel is connected to receive the aluminium chloride produced and to condense it.

In a modification of the invention, the invention consists in apparatusv for preparing anhydrous aluminium chloride comprising: a two-part corrosion-resistant vessel for containing molten zinc-aluminium allow having a dividing wall formed as an underflow bafile; a pipe extending from beneath the alloy surface in a first part of the vessel and to the vicinity 'of the alloy surface in a second part of the vessel when the apparatus is in use and capable of conveying molten alloy from the first to the second part ofthe vessel and a connection for feeding chlorine into the alloy contained in the second part. A second vessel may be provided to receive the aluminium chloride prowater-cooling means. g

The invention still further consists in aluminium -chloride Whether as a vapour or in solid form, when prepared by the method or in the apparatus according tothe invention.

may be provided with The method and apparatus according to the invention may be'described with reference to the accompanying drawings the single figure of which isa 'section through a suitable form of apparatus.'-

1a and 112. A chlorine inlet pipe 3 protrudes'into part 1b.

via gate 6 leads into part 1b.

, '55 The apparatus shown consists of a vessel]. provided 1 with underfiow baffle 2 which divides it into'two parts ,ture of from40 C. to C. and aluminium chloride powder of 99% purity is collected from the outlet 11 in a suitablecontainer such as a polythene bag.

However, if the aluminium chloride is required in massive or crystalline form, then a further stage is required in which the powder is heated, for. example, 190 C. at 2.5 atmospheres pressure, and then allowed to solidify. Alternatively, a high purity product may be obtained by sublimation in a suitable apparatus to produce massive crystals.

In some manufactures, e.g., the manufacture of titanium oxide-based pigment, vapourized A101 can advantageously be used, e. g., for mixing with the TiCl; being hydrolyzed. If this vapourized AlCl is required it may be drawn off at A. Vapourized AlCl may also be used for vapour phase catalysis. 1

usually contains impurities. such as iron, silicon and copper. When such scrap aluminium is used as a feed to Vessel 1, the iron and silicon separate outand'form a dross on the surface which. maybe removed. Some I copper, however, remains in solution and may circulate to chlorinating portion 112 but it has no interfering effect.

Thus no harmful impurities are allowed to pass into portion 112 since circulationbetween'the two portionsof vessell is effected through pipe 4 which is fed from near ing aluminium and zinc. The zincacts as avehicle to hold the aluminium and thereby enables the reaction to be carried out at a lower temperature than if aluminium alone were used, thus making itpossible to use-steel equipment throughout.

The ratio of zinc to aluminium in the alloy in vessel 1 is not critical although a working ratio might be about Water-cooling coils 7 are provided in part it: to take .up the heat of reaction, as described below.

Above the chlorine inlet pipe 3, in an extension of vessel 1, is a steel grating 8,'upon which a bed of granulated aluminium 9 is provided. The space above this bed, if

When operation is commenced, a zinc-aluminium alloy is added to vessel 1 and initially heated to 430 C.-

It is a logical extensioniof this process to charge to vessel 1 a scrap alloy containing, for" example, 96% zinc, 4% aluminium and a little copper, for example, scrap Mazak (Mazak is a registered trade mark), instead of feeding scrap aluminium to a melt of- Zinc to give the required range of working ratios of ZnzAl. Thus, it follows that a further advantage may accrue from our process, namely that operating the apparatus on a feed of scrap Mazak, a good yield of aluminium chloride may be produced and, in addition, the removal of the aluminium from the alloy as AlCl will produce a grade of zinc metal remaining in the reaction vessel of equivalent to Patented Oct. 13, 1 964 I claim: 1. A method of preparing anhydrous aluminium chloride which comprises: retaining a molten zinc-aluminium alloy at a temperature of from 430 C. to 500 C. in a vessel divided-into two portions by an underfiow baffle;

'passing'chlorine gas into one portion of the vessel to form aluminium chl'o'rid'evapour; allowing said aluminium chloride vapour to pass upwards through a layer of pieces of aluminium to rid itof traces-of free chlorine, cooling the molten zinc-aluminium alloy in the other portion of the vesseland passing the molten-alloy thus cooled into the first portion of the vessel'for furtherreaction with chlorine vapour at a temperature ofbetween 430 C. and 500C., thereby causing the Warmer molten alloy thus formed to pass back beneath the underflow baflle to be cooled-' 2. A method as claimed in claim 1, in which the aluminium chloride vapour which has been purified by contact with the layer of pieces of aluminium is condensed to solid aluminium chloride.

References Cited in the file of this patent UNITED STATES PATENTS 877,243

Pardee July 15, 1958 

1. A METHOD OF PREPARING ANHYDROUS ALUMINUM CHLORIDE WHICH COMPRISES: RETAINING A MOLTEN ZINC-ALUMINIUM ALLOY AT A TEMPERATURE OF FROM 430*C. TO 500*C. IN A VESSEL DIVIDED INTO TWO PORTIONS BY AN UNDERFLOW BAFFLE; PASSING CHLORINE GAS INTO ONE PORTION OF THE VESSEL TO FORM ALUMINIUM CHLORIDE VAPOUR; ALLOWING SAID ALUMINIUM CHLORIDE VAPOUR TO PASS UPWARDS THROUGHA LAYER OF PIECES OF ALUMINIUM TO RID IT OF TRACES OF FREE CHLORINE, COOLING THE MOLTEN ZINC-ALUMINIUM ALLOY IN THE OTHER PORTION OF 